The development, function and structure of the neuromuscular junction will be studied. The genes coding for the acetylcholine receptor and the acetylcholine esterase will be cloned using recombinant DNA technology. The structure of these genes will be determined and their regulation studied using probes for mRNA. The expression of the acetylcholine receptor and esterase genes will be measured during development of the neuromuscular junction and after denervation. Mono-clonal antibody specific for antigens of the neuromuscular junction will be produced. These antibodies should be highly specific probes for the study of synapse structure and function. Immunogens will include basement membrane preparations and muscle cells rich in synaptic endings. The elucidation of the defect in the neuromuscular disease, myasthenia gravis, will continue.